Electric switch



F. E. LUEBKERT ELECTRIC SWITCH Nov. 24, 1953 2 Sheets-Sheet 1 Filed Feb. 16,, 1950 Q Q N NM NM INVENTOR. FRED .5. L UEBKERI BY /ZC ATTORNEK F. E. LUEBKERT ELECTRIC SWITCH Nov. 24, 1953 2 Sheets-Sheet 2 Filed Feb, 16 1950 HTTOQNE 4 I Patented Nov. 24, 1953 ELECTRIC SWITCH Fred E. Luebkert, Brooklyn,

N. Y., assignor of one-half to Maxwell E. Sparrow, New York,

Application February 16, 1950, Serial No. 144,439

9 Claims.

This invention relates to improvements in electric switches, and particularly to improvements in switches for conducting large currents and especially such switches of the knife blade type.

The desirability of achieving a high contact pressure between the blade of the switch and the fixed post or contact in switches having a high current carrying capacity has long been recognized. Such high contact pressure cannot feasibly be achieved by the mere resilience of the parts; and therefore switches of the knife blade type have been constructed in which the desired contact pressure is obtained by suitable clamping structure arranged to be actuated after the movable contact, or blade, is in the switch closed position, and to be released before moving the blade from the closed position. Such prior switches have included a pivot post electrically connected to one of the terminels of the switch, a pair of blades pivotally disposed on opposite sides of the pivot post and engaging on opposite sides of a fixed post when in the switch closed position, and an operating member connected to the blade clamping structure and movable relative to the blades for clamping the blades on the posts only when the blades are in switch closed position. When the blades are in switch-open position, locking means prevent movement of the operating member relative to the blades and such operating member is then manipulated for the purpose of swinging the blades. However, the prior arrangements for locking the operating member relative to the blades during the switchopen position of the latter have all been relatively complicated, subject to mechanical breakdown. and required the exertion of excessive force in effecting the movement from locked to unlocked position.

Therefore, an object .of this invention is to provide in a relatively large current conducting capacity switch of the knife blade type including clamping means for effecting a high contact pressure between the posts and the swinging blades when the latter are in switch-closed position, improved locking devices for preventing operation of the clamping means while the blades are in open position, which locking devices are released when the blades are in switch-closed position.

Another object of this invention is to provide, in a switch of the type described, locking means for the blade clamping mechanism which is movable from the locked to released position by the exertion of a minimum effort on the part of the operator to thereby effect the smooth and easy movement of the switch blades.

Still another object of this invention is to provide, in a switch of the kind described, a locking assembly for the blade clamping mechanism which is so arranged and constructed as to permit the easy adjustment of the several parts thereof to thereby insure the proper operation of the locking assembly at all times and in all suitable environments.

A further object of this invention is to provide, in a switch of the kind described, ,a locking as sembly for the blade clamping mechanism which is so arranged and constructed as to permit its attachment to existing switches with a minimum of modification, and also so as to permit the replacement of the several parts thereof without disturbing the operation of the major components of the switch.

With these and other objects and advantages, apparent in the following description and in the accompanying drawings forming a part thereof, in view, my invention consists in the novel combination, arrangement and details of construction of the several parts disclosed therein and more particularly defined in the appended claims.

In the drawing:

Figure 1 is a side elevation of a knife blade switch in open position and embodying a locking device for the blade clamping mechanism constructed according to an embodiment of my invention;

Figure 2 is a side elevation of the switch illustrated in Figure 1, and showing the relationship of the several parts when the blades have been pivoted towards closed position, but with the blades'not yet in full closed position;

Figure 3 is a fragmentary front view of a portion of the switch in the position illustrated in Figure 2, and showing the details of the locking assembly;

Figure 4 is a side elevation of the switch with the blades in full closed position, and before the clamping mechanism has been moved to blade clamping position;

Figure 5 is a side elevation of the switch in full closed blade clamped position;

Figure 6 is a fragmentary side elevation of elements of the locking mechanism, with the switch shown in broken lines having the blades in the position illustrated in Figure 2; and

Figure 7 is a fragmentary side elevation, similar to that of Figure 6, with the blades of the switch in the position illustrated in Figure 4.

Referring to the drawings, wherein like reference numerals indicate like parts, a switch, of the knife blade type, having a great current carrying capacity, is generally indicated by the reference numeral H). The switch l6 includes a pair of terminal blocks H and l2, formed of a highly conductive material, such as copper, and mounted upon an insulating mounting board l3 in spaced apart relationship. A fixed post |4, formed of a plate of highly conductive material, extends outwardly from the terminal block H. An arcuate slot I5 is formed in the fixed post I4, and opens through the outer free edge of the latter. Stop forming blocks l6 are secured to the opposite side faces of the fixed post |4, adjacent to the base thereof. A pivot post formed of a plate of highly conductive material, extends outwardly from the terminal block l2. Switch open stops i8 are secured to the opposite side faces of the pivot post adjacent the base thereof. The knife blade of the switch is formed of a pair of spaced apart, elongated, highly conductive plates l9 and 29. The pair of plates l9 and 26 are pivotally connected, adjacent one end thereof, to the pivot post H by the pivot member 2| extending therethrough. The pivot member 2| is rotatable with respect to the pivot post l1, and also with respect to the knife blades I9 and 29. A substantially triangular operating member 22 is rotatably disposed upon the pivot member 2|. A circular disc or plate 23 is fixed upon the pivot member 2| and is interposed between the operating member 22 and the knife blade l9. Diametrically opposed pins 24 and 25 are fixed upon the disc 23 and are received loosely within the arcuate slots 26 and 21 extending through the operating member 22, to thereby provide a lost motion connection between the operating member 22 and the pivot member 2|. An insulated handle 28 is fixed to the operating member 22 and provides means for actuating, or moving, the knife blades l9 and from the open to closed position thereof, and from the closed to open position, and also actuating means for the blade clamping mechanism to be described hereinafter.

The blade clamping mechanism includes a shaft 29 rotatably carried by the free ends of the blades l9 and 26, and positioned to be received within the arcuate slot |5 of the fixed post when the blades are swung to closed position. A crank member 39 is fixedly attached to the shaft 29, and a connecting rod 3| is pivotally connected at its opposite ends to the operating member 22 and the crank member 30. Therefore, rocking of the operating member 22 will effect rotation of the pivot member-2| and the shaft 29 relative to the blades I9 and 20. Both the pivot member 2| and the shaft 29 are formed with screw threads upon the ends thereof which extend through the knife blade 2|]. These threaded ends of the pivot member 2| and the shaft 29 are received by internally threaded members 32 fixed upon the outer surface of the knife blade 20. Therefore, rotation of the pivot member 2| and the shaft 29 in one direction, relative to the knife blades I9 and 29, will effect the drawing together of the knife blades |9 and 26 for clamping upon the fixed post M and the pivot post l'i. Rotation of the pivot member 2| and the shaft 29 in the opposite direction will effect the spreading apart of the knife blades in order to release them to provide for the easy swinging of the knife blades relative to the posts l4 and IT. The structure so far described represents a well known switch of the knife blade type, including clamping mechanism for effecting tight engagement between the knife blade and the terminal posts when the blades are in switch closed position.

Applicants invention, which will now be described, relates to a novel locking assembly for preventing rotation of the pivot member 2| and the shaft 29 relative to the knife blades I9 and 20 in a direction which would effect drawing together of the knife blades, whenever the latter are in the switch open position. The locking mechanism, forming this invention, includes an arm 33 fixed to one of the knife blades, in this case blade l9, and secured thereto by the fastening members 34. The arm 33 extends beyond the side edge of the blade l9, and has a roller 35 secured to it projecting laterally from the free end, thus constituting an abutting member. A substantially rectangular plate 36 is pivotally connected adjacent to one end to the connecting rod 3| by the pivot 31. A spring 38, having its opposite ends connected to the connecting rod 3| and to the plate 36, constantly urges the latter to assume a position at right angles to the length of the connecting rod 3|. An adjusting member 39 is rotatably carried by the connecting member or rod 3|, and is formed with an eccentric head thereon which is loosely received within the opening 66 formed in the plate 36. The eccentric adjusting member 39 provides a stop for preventing the pivoting of the plate 36 to the right angular position imposed upon it by the spring 38. An inclined laterally extending projection 4| extends from the end of the plate 36 removed from the pivot 31. The projection extends in a direction opposite to the roller 35 on the arm 33, and is engageable with the latter to prevent movement of the connecting rod 3| relative to the knife blades l9 and 26. A lock releasing member, generally referred to by the numeral 42 is carried by the insulating mounting board l3. The lock releasing assembly 42 includes a housing 43 secured to the board l3, and formed with an internally threaded bore 44. A threaded bolt 45 is received within the bore 44, and is provided with a head 46 for engagement with the plate 36, when the blades l9 and 26 are swung to closed position. A look nut 41 is threaded upon the bolt 45 between the head 46 thereof and the housing 43, for retaining the bolt 25 in selected position.

Beginning with the switch in full open position, as illustrated in Figure l, the projection 4| of the plate 36 is engaged with the roller 35 and is disposed beyond the center of the latter, so that swinging of the handle 28 in the direction of the arrow, for pivoting the blade about the pivot member 2|, will not also be effective to rotate the operating member 22 and the bell crank in the direction of the arrow. That is, the projection 4| and the roller 35, when engaged as shown in Figure 1, will prevent longitudinal movement of the connecting rod 3| relative to the blades l9 and 20. The position of the projection 4| with respect to the center of the roller may be adjusted in this position by rotating the eccentric stop 39 carried by the connecting rod 3|. Therefore, the clamping mechanism will be prevented from drawing together the blades l9 and 20 during the movement of the latter towards the fixed post l4.

When the blades l9 and 26 have been pivoted towards the closed position, and reached a point just before engagement of the blades with the stops IS on the fixed post M as shown in Figure 2, the head 46 of the releasing mechanism 42 engages the edge of the plate 36. The timing of the engagement of the head 46 with the edge of the plate 36 is determined, and may be adjusted, by the extension of thebolt from the housing 43. The relationship, and coaction, of

the various parts of the locking mechanism, in the position illustrated in Figure 2, is best seen in detail in the enlarged view of Figure 6. Further movement of the knife blades l9 and 2-6 to the full closed position, illustrated in Figure 4, will result in the pivoting of the plate 36 relative to the connecting rod 3|. That is, the head 46 of the releasing assembly will move the projection 4] beyond the center of the roller 35. Further movement of the handle 28 in the direction for closing the switch, will cause the operating member 22 to pivot or rotate relative to the blades l9 and and to effect longitudinal movement of the connecting rod 3| relative to the blades. Such longitudinal movement of the connecting rod will no longer be resisted by the projection 4| of the pivoted plate 38, since such projection will now be free to ride over the surface of the roller 35. Therefore, once the head at of the releasing assembly has moved the plate 36, further rotation or movement of the handle 28 will effect the rotation of the operating member 22 and crank 30 for clamping the plate or blades 19 and 263 upon the opposite side surfaces of the fixed post l4 and the pivot post ll, thereby obtaining the desired contact pressure between the several parts of the switch. The position of the several elements of the locking assembly when the head 46 has raised the projection 4| relative to the roller is best seen in Figures 4 and 7 of the drawing, while the position of the parts following further movement of the handle 28 for clamping the blades is illustrated in Figure 5.

When it is desired to open the switch, the handle is moved in the direction of the arrow in Figure 5, and such initial movement will effect movement of the connecting rod in the direction of the arrow. Such movement of the connecting rod 3! will effect release of the clamping means, so that further downward movement of the handle will swing the knife blades [9 and 20 away from the fixed post M. During the movement of the connecting rod 3| relative to the knife blades, the inclined surface of the projection 4| on the plate 36 will ride over the roller 35 carried by the arm 33, and will assume the position thereof illustrated in Figure 1.

From the above description of the structure of my locking assembly, and the operation thereof, it can be seen that the clamping assembly, for obtaining the desired contact pressure between the blades and the posts 14 and H, may only be actuated when the blades are in the full closed position. Therefore, movement of the handle 28, when the blades are in any position other than the full closed position, will not effect the drawing together of the blades l9 and 20, and therefore the free and easy movement of the blades i9 and 20 is assured.

Having thus described a specific illustrative embodiment of my locking device for a switch of the knife blade type, it is to be understood that various modifications and changes therein may be effected without departing from the scope of the invention as defined in the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. An electric switch comprising an insulating panel; a pair of spaced apart posts mounted upon said panel, one of said posts constituting a fixed contact; a movable contact carried by the other of said posts and movable into and out of engagement with said fixed contact; clamping means at each of the opposite ends of said movable contact for exerting pressure be.- tween said movable contact and said posts in the switch closed position of said movable contact; operating means including a connecting rod operatively extending between said clamping means and movable relative to said movable contact in one direction to effect the clamping action of said clamping means and in the opposite direction to release the clamping action; and a locking assembly operative to prevent movement of said connecting rod in said one direction during switch closing movement of said movable contact, said locking assembly including motion arresting means carried by said movable contact and by said connecting rod adapted to lockingly engage when said movable contact is in switch open position and said clamping means are released, and unlocking means carried by said panel engageable with said motion arresting means after said movable contact has reached the end of its travel in the closing direction and effecting the release of the locking engagement thereof to permit movement of said connecting rod in said one direction for effecting the clamping action of said clamping means, said motion arresting means including a laterally extending element, and a pivoted member having a lateral projection engaging said element beyond the axis thereof when said movable contact is in switch open position, said unlocking means being engageable with said pivoted member when said movable contact is in switch closed position and effecting the rocking of said pivoted member for positioning said lateral projection above the axis oi said element, said unlocking means including a headed member adjustably movable relative to said panel for regulating the engagement of said headed member with said pivoted member with respect to the position of said movable contact.

2. In an electric switch including a fixed contact, a cooperating contact movable into and out of engagement with said fixed contact, clamping means for exerting pressure between said contacts in the switch closed position thereof, and an operating member carried by said movable con tact for movement relative thereto in one direction to efiect the clamping action of said clamping means and in the opposite direction to release the clamping action; locking means for preventing movement of said operating member in said one direction when said movable contact is in switch open position comprising releasably abutting means carried by said movable contact and said operating member adapted to engage when said movable contact is in switch open position, and releasing means operatively engaging said abutting means when said movable contact has reached the end of its travel in the switch closing direction, the engagement of said releasing means with said abutting means efiecting disposition of the latter for movement of said operating member in the pressure applying direction, said abutting means including an element on said movable contact, and a pivoted member carried by said operating member, said pivoted member being formed with a lateral projection engaging said element beyond the axis of the latter when said movable contact is in switch open position, said releasing means engaging said pivoted member for moving the latter above the axis of the element to permit sliding of the lateral projection relative to the latter.

3. In an electric switch, locking means as set forth in claim 2, wherein said releasing means includes an extendible member adjustable for regulating the contact thereof with said pivoted member with respect to the movement of said movable contact.

4. In an electric switch, locking means according to claim 3, including a spring constantly urging said pivoted member to a position in which said lateral projection is disposed beyond the axis of said element.

5. In an electric switch, locking means according to claim 4, including an adjustable stop carried by said operating member and engaging said pivoted member for limiting the movement of the latter in the spring urged direction.

6. An electric switch comprising an insulating panel; a pair of spaced apart posts mounted upon said panel, one or said posts constituting a fixed contact; a movable contact pivoted at one end on the other of said posts and movable into and out of engagement with said fixed contact; clamping means at each of the ends of said movable contact adapted to exert pressure between said movable contact and said pair of posts when said movable contact is in the switch closed position; operating means for said clamping means including a connecting rod operatively connected between said clamping means and movable in one direction relative to said movable contact to effect the clamping action of said clamping means; locking means carried by said movable contact and said connecting rod adapted to resist movement of the latter in said one direction when said movable contact is in the switch open position; and releasing means on said panel operatively engaging said locking means when said movable contact reaches the end of its travel in the switch closing direction and adapted to release said looking means to permit movement of said connecting rod in said one direction for effecting the clamping action of said clamping means, said locking means including a pivoted plate member carried by said connecting rod, an element fixed relative to said movable contact and interposed in the path of travel of said plate member when the latter is moved with said connecting rod in said one direction; said releasing means displacing said plate member when said movable contact reaches the end of its travel in the switch closing direction so that said element no longer blocks the movement of said plate member and said connecting rod.

7. An electric switch according to claim 6, wherein said locking means include an abutting member fixedly carried by said movable contact, a plate member having a portion engageable with said abutting member, a spring constantly urging said plate member to a position in which said abutting member is interposed in the path of travel of said portion when said connecting rod is moved in said one direction, and an adjustable stop member carried by said connecting rod and engageable with said plate member for regulating said spring urged position of said plate member; and wherein said releasing means engages said plate member when said movable contact reaches the end of its travel in the switch closing direction and displaces said plate member in opposition to the spring force to a position in which said abutting member is ofiset relative to the path of travel of said portion of said plate member moving with said connecting rod in said clamping direction.

8. An electric switch according to claim '7, wherein said portion on said pivoted plate member consists of a laterally extending projection inclined relative to the path of travel thereof and adapted to ride over said abutting member when said connecting rod is moved in the opposite direction for releasing said clamping means.

9. An electric switch according to claim 8, wherein said releasing means includes a headed member extending adjustably from said panel for regulating the timing of the engagement thereof with said pivoted plate member and the displacement of the latter effected when said movable contact is in switch closed position.

FRED E. LUEBKERT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,288,134 Hoye June 30, 1942 2,363,287 Bayer Nov. 21, 1944 FOREIGN PATENTS Number Country Date 216,276 Germany Oct. 20, 1908 

